There are known, in prior art, decorative pieces which are intended to be set into a wearable object, such as a watch or jewellery, and which consist of setting of an aesthetic element on the parts of said wearable object acting as support.
For this purpose, the support is produced in a metallic alloy and is machined so that housings appear. During this machining, catching means having the shape of hooks are produced. In general, these hooks are produced with the material forming the wearable object, i.e. in a monobloc fashion with the object. When an aesthetic element, such as a precious stone, has to be set, the latter is placed in a housing and the catching means are folded down, cold, by plastic deformation in order to retain said aesthetic element in the housing. This setting method is widely used for setting precious stones on metal supports because the latter has an advantageous plastic deformation capacity. This capacity is even more advantageous with precious metals such as gold because these precious metals are ductile and can be shaped easily. The cold plastic deformation of crystalline metals is possible thanks to the movements of dislocations present in the crystal lattices. The elastic limit, i.e. the stress beyond which a material begins to deform plastically, of a crystalline alloy depends upon the elements which form the latter and also the thermomechanical history of the alloy. For traditional settings, alloys which have relatively low elastic limits are generally chosen in order to facilitate the work of the setter. In addition to a relatively low elastic limit, it is necessary that the alloy has sufficient elongation before rupture in order to be able to fold down the catching means without them breaking. As with the elastic limit, this elongation is the consequence at the same time of the elements present in the alloy and the thermomechanical history of the latter. For example, gold alloys used in the manufacture of timepieces have an elastic limit of the order of 200-400 MPa and a breaking elongation of 20-40%. Stainless steels of type 1.4435 have an elastic limit of 200-300 MPa and a breaking elongation of 25-45%.
Nevertheless, a disadvantage of this method is that it is limited to supports produced in ductile metals or ductile metallic alloys. Now, more and more timepieces are produced in materials which do not have plastic deformation, often hard and/or fragile materials, such as for example ceramics, silicon, composites or even intermetallic alloys.
Consequently, it is no longer possible to use the current method for setting aesthetic elements such as for example precious stones.
This setting operation is therefore replaced by a glueing operation. The disadvantage of glueing is not guaranteeing 100% retention of the stones because, in contrast to setting, this technique does not involve mechanical retention of the stones. In fact the glued zones being in the majority of cases exposed to the exterior environment (humidity, perspiration, UV, air pollution . . . ), the retention of the bonding over the long term is made difficult. Consequently, retention of the stones is not guaranteed, which is not acceptable for quality products.